SINCLAIR LEWIS' "Elmer Gantry," which shocked, amused, confounded, but rarely bored readers back in 1927, has been lifted from the pages of the justifiably controversial novel and impressively transformed into an exciting film. The briskly paced drama of a religious opportunist, his colleagues and his times utilizes the tools of the motion picture in expert fashion.

The result, as exposed in color and old-fashioned, small screen at the Capitol Theatre yesterday, is a tribute to the artistry of Richard Brooks, the scenarist-director, and a fine cast. They make this story of the devil-may-care revivalist a living, action-packed, provoking screen study, largely devoid of the novel's polemics, that captures both the eye and mind.

Perhaps devoted readers will blanch at the metamorphosis wrought here. The book, it may be recalled, followed Elmer Gantry all over the country for a long period of time. It did not hesitate in its condemnation of his charlatanry, his lusts, his adultery, and of course, his blatant opportunism both in sex and religion. And, Mr. Lewis digressed often into pamphleteering that obscured his principal characters in a welter of bias and tub-thumping discussion. The book also paid copious attention to the many, often colorful and often pitiful people affected by Gantry during his undulant career.

Mr. Brooks, an obviously dedicated artisan who has owned the property for some five years and shaped the script over the past two years, has made astounding but effective changes in the original. Many of the characters are gone, some have been changed completely, scenes have been shifted and emphasis on other principals has been raised or lowered. But Gantry and his company emerge, in essence, in bold, rough, sacrilegious but nearly always human, believable terms.

The Gantry we see now is not ordained, Baptist, Methodist or any other sect. but an expert spieler and a lusty, ribald drummer who sees a good thing in Sister Sharon Falconer's evangelical troupe and cons his way into her tent-tabernacle, her graces and her heart. And, in focusing only on this period in Gantry's peripatetic career. Mr. Brooks has given point and action to the sprawling, contentious work that was the novel.

This is not to say that it has been transformed into a simple adventure. It is a complex story running nearly two and a half hours, but its length is hardly noticeable since its many vignettes, each sharply presented, are joined into a theme that somewhat changes Gantry, Sister Falconer, et al., from Lewis' conception but has them shape up as forceful, and often memorable, individuals. Perhaps the sleaziness of some forms of evangelism is not too pressing an issue these days but in "Elmer Gantry" it is made authentic and engrossing.

As Gantry, Burt Lancaster has one of his fattest roles and one to which he gives outstanding service. As has been noted, he is not quite Lewis' boy, but he is still the smirking, leering lecher who tells his fellow salesmen an off-color yarn with the same ease that he thumps the Good Book and shouts the name of Jesus with amazing frequency. If he is not completely redeemed at the film's end, he indicates that his love for the ill-fated Sharon Falconer is real and not mere lust.

The character of Sister Falconer, as played by Jean Simmons, also has been subjected to change by Mr. Brooks. And for the better, too. On Miss Simmons' finely etched portrayal of the evangelist, the erstwhile Katy Jones of Shantytown, is a truly devout preacher of the Gospel. Her love of Gantry and death in the climactic conflagration that destroys the Waters of the Jordan tabernacle is a pointed and poignant lesson. Completely altered, too, is the character of Jim Lefferts, no longer a seminary classmate of Gantry but now a cynical reporter who, as played in serious but restrained style by Arthur Kennedy, evolves as a three-dimensional realist and not a type.

Shirley Jones certainly is different from the sweet heroine of "Oklahoma!" as the blonde, brash prostitute first violated by Gantry. And, the success-conscious George Babbitt, as neatly played by Edward Andrews: Dean Jagger's worried, but purposeful manager of Sister Falconer, and Patti Page, as the tabernacle's choral soloist, add professional support to the principals.

Scenes in a brothel and a speakeasy and the salvation hungry faces of the tabernacle crowds strikingly illuminate the excitement, the follies, the tawdriness and the tragedy of the era. Now, the mustiness of the printed page of 1927 is gone. This "Elmer Gantry" makes the age and the people vividly come alive.